I have a 2009 C-350 and the engine will knock on startup after the engine has been turned off awhile or sitting overnite, this knock does not happen every time it is started so I really can't pin it down to know exactly when it will happen.
I have taken it to the dealer several times to get it checked out and they don't have an answer for me. The last time I took it in was this week and they told me it was probably the injectors building up, I really don't think that is the problem, the sound is a muffled knock that lasts about 3 seconds so it is hard to diagnose.
Has anyone out there had this problem and if you did how was it reparied ?
Thank you